1. Field of the Invention
The present invention relates to a room temperature curable polymeric composition which is useful as constructional sealing material, coating material, encapsulating or potting material for electric and electronic components, fiber-treating agent, adhesive for automotive, constructional and electric or electronic uses, and so forth.
2. Description of the Prior Art
As a condensation-curing type room temperature curable composition comprising an alkylene oxide polymer or an organopolysiloxane as base polymer, there have been known those of one-pack type in which the amount of crosslinking agent is reduced to an utmost degree and crosslinking rate is enhanced by hydrolysis of hydrolyzable groups introduced into the base component and those of two-pack type in which a crosslinking agent and a curing agent are enclosed in separate packs.
However, the one-pack type compositions need a considerable length of time for curing to their deep portions, though they have a high rate of cure from the surface thereof. The two-pack type compositions are comparatively better in deep portion curing properties, but they are disadvantageous in that, because their two parts in separate packs are not formulated for a mixing ratio of 1:1 by volume or by weight, they are poorly processable in quantity measurement or mixing operations and are not well suited to use with mixing machines or the like. In the two-pack type compositions, furthermore, suitable ranges for addition amounts of crosslinking agent and curing agent necessary for complete cure to deep portions of the composition are very narrow and, accordingly, it is necessary to specify strictly the addition amounts of the crosslinking agent and curing agent or to add water as a deep portion curing agent.
Recently, curable compositions comprising as main constituents thereof a so-called crosslinkable silyl group-containing alkylene oxide polymer, i.e. an alkylene oxide polymer containing a hydrolyzable silyl group whose hydrolysis is accompanied by crosslinking, and an epoxy resin have been developed (See Japanese Pre-examination Patent Publication (KOKAI) Nos. 61-268720 (1986), 62-283120 (1987), 2-145674 (1990), 2-145675 (1990) and 2-228365 (1990)). In this type of compositions, crosslinking and curing of the crosslinkable silyl group-containing alkylene oxide polymer proceeds separately from that of the epoxy resin. Namely, the crosslinkable silyl group-containing alkylene oxide polymer is cured by crosslinking which results from formation of siloxane linkages under the action of moisture, whereas the epoxy resin is cured by crosslinking which accompanies catalytic opening of epoxy rings.
Major uses of these curable compositions include, for example, application as an adhesive for areas where aseismatic properties are required in the fields of electric and electronic industry and construction materials. In such applications, the curable compositions are required to have high cure rate and adhesive strength, and cured products thereof are required to be elastic.
However, the above-mentioned curable compositions comprising a crosslinkable silyl group-containing alkylene oxide polymer and an epoxy resin as main components need a considerable length of time for curing to deep portions thereof, because the silyl group-containing polymer is cured by moisture in air. On the other hand, where water is preliminarily added to the curable composition in order to shorten the period of time necessary for deep-portion curing, shelf life of the composition is lowered.